1. Field of the Invention
This invention relates to thermal storage and is particularly directed to methods and apparatus for storing thermal energy in solar energy systems and the like.
2. Description of the Prior Art
In recent years, the world has become aware that its oil reserves are finite and are approaching depletion. As a result, there has been considerable study of alternative energy sources. One of the most promising of these alternatives is solar energy. However, due to diurnal temperature changes, cloudiness and various other matters, the problem of thermal storage has been one of the major obstacles to widespread acceptance of solar energy systems, especially for large scale systems, such as municipal utilities.
One technique for solving the problem of thermal storage is taught in U.S. Pat. No. 4,124,061, issued Nov. 7, 1978, to Rex. C. Mitchell et al. This technique constituted a significant step forward in the art of thermal storage. However, the temperatures which the Mitchell et al system is capable of storing are extremely limited. Consequently, the search for improved thermal storage concepts has continued.